One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,6)(4,5)(7,8)(9,10)(11,20)(12,17)(13,28)(14,18)(15,19)(16,22)(21,36)(23,31)(24,30)(25,34)(26,39)(27,35)(29,32)(33,37)(38,40) involution — undirected(9,11,13,22,15,23,14,29)(10,16,18,20,19,32,28,31)(12,24,26,37,25,38,27,21)(17,33,35,30,34,36,39,40)(2,5)(6,8)(9,12,14,27,15,25,13,26)(10,17,18,35,19,34,28,39)(11,21,22,24,23,37,29,38)(16,30,31,33,32,40,20,36)(9,12,13,26,15,25,14,27)(10,17,28,39,19,34,18,35)(11,21,29,38,23,37,22,24)(16,30,20,36,32,40,31,33)(1,3,4,7)(2,6,5,8)(12,25)(17,34)(21,37)(24,38)(26,27)(30,40)(33,36)(35,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.